DESCRIPTION: Vitamin D plays an essential role for the growth and maintenance of healthy bones. Fortification of fresh milk and infant formula with vitamin D has played an important role in eradicating rickets in children, whereas, overfortification can cause vitamin D intoxication and other serious consequences. Thus, it is imperative that milk samples and infant formula have the correct vitamin D concentration as stated on the label. However, the current methods for the determination of vitamin D are very time consuming. It requires highly skilled personnel to perform the experiments and takes several days for completion. By the time they receive the reports, their milk products have already been shipped to the market and purchased. Therefore, the goal of this research project is to develop a rapid, sensitive, and specific assay for vitamin D in milk and infant formula utilizing high affinity binding between biotin and avidin coupled to horseradish peroxidase to develop an enzyme-linked immunosorbent assay (ELISA) for vitamin D. Because the sensitivity of ELISA depends on the detection limit for the calorimetric substrates used, the investigator proposes to utilize chemiluminescence ELISA substrates. The investigator proposes that the sensitivity can be increase at least 3 orders of magnitude over conventional calorimetric assay. The specific aims for this Phase I proposal are to:1. develop a rapid and sensitive non-radioactive assay to determine vitamin D concentration in milk using a combination of chemiluminescence and biotin-avidin technology, and 2. develop a rapid and sensitive non-radioactive assay to determine vitamin D concentration in infant formula using a combination of chemiluminescence and biotin-avidin technology. Eventually, a simple commercial assay kit will be developed for marketing that will allow an on-site analysis of vitamin D contents in milk and infant formula. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE